Very low or even negative prices, during episodes of renewables overproduction (typically when wind blows or sun shines way over demand), are more and more common.

https://en.wikipedia.org/wiki/Negative_pricing#Electricity

Reciprocally as more and more less tolerated grid backup (greenhouse-gas emitting fossils or dangerous nuclear) disappear episodes of under-production will be more common, and during those electricity price will soar.